Backward-aging jellyfish
Also known as the immortal jellyfish or Turritopsis doohmii. According to National Geographic, it has discovered a means to avoid death by really reversing the ageing process.
Ever-growing lobsters
The scientific world is divided on whether or not these creatures of the red ocean are physiologically immortal; they grow and breed until they pass away, with sickness being the leading cause of mortality rather than old age.
Sturdy turtles
The saying "slow and steady wins the race" is true. Researchers have discovered that turtles' organs appear to maintain their structural integrity throughout a long lifespan.
Regenerating flatworms
These grotesque creatures, also known as planarian worms, are renown for their capacity for regeneration, which allows a worm to divide into two distinct ones when sliced lengthwise or crosswise.
Tough whales
The oldest bowhead recorded reached the age of 211. Whales rank among the largest living creatures in the planet and have long life spans.
Radiation-resistant bacterium
The poly-extremophilic bacteria Deinococcus radiodurans is not just radiation-resistant. The amazing DNA repair reaction of these immortal creatures allows them to both die and then resurrect.
Tardigrade
Any attempt to harm a tardigrade will rapidly learn that they are dealing with creatures who are essentially immortal.